One type of wireless communication network is a wireless mesh network. The wireless mesh network is a network made up of Radio Frequency (RF) transceivers organized in a mesh topology. Wireless mesh networks may consist of mesh clients, mesh routers and mesh gateways. Clients can be computer nodes, cell phones and other devices and a mesh router forwards traffic to and from gateways which may or may not be connected to the Internet. A mesh network offers redundancy in that when one node is inoperative, other nodes can still communicate with each other either directly or through intermediate nodes.
An emergency communication network comprising mobile devices is typically of limited size and range. One example of such a network is a Mobile Ad Hoc Network (MANET), which is a continuously self-configuring, infrastructure independent network of mobile devices connected without wires. To provide mission-critical communications, the emergency communication network should have an (i) infrastructure that is resilient, redundant, and highly available; (ii) communications should be reliable; (iii) communications should be secure; and (iv) point-to-multipoint communication should be supported. The mission-critical communications may include both mission-critical voice and mission critical data.
According to the National Public Safety Telecommunications Council (NPSTC), mission-critical voice communications should provide the following features:
Direct or Talk Around: This mode of communications provides public safety with the ability to communicate unit-to-unit when out of range of a wireless network OR when working in a confined area where direct unit-to-unit communications is required.
Push-to-Talk (PTT): This is the standard form of public safety voice communications today—the speaker pushes a button on the radio and transmits the voice message to other units. When they are done speaking they release the Push-to-Talk switch and return to the listen mode of operation.
Full Duplex Voice Systems: This form of voice communications mimics that in use today on cellular or commercial wireless networks where the networks are interconnected to the Public Switched Telephone Network (PSTN).
Group Call: This method of voice communications provides communications from one-to-many members of a group and is of vital importance to the public safety community.
Talker Identification: This provides the ability for a user to identify who is speaking at any given time and could be equated to caller ID available on most commercial cellular systems today.
Emergency Alerting: This indicates that a user has encountered a life-threatening condition and requires access to the system immediately and is, therefore, given the highest level or priority.
Audio Quality: This is a vital ingredient for mission critical voice. The listener must be able to understand without repetition, and can identify the speaker, can detect stress in a speaker's voice, and be able to hear background sounds as well without interfering with the prime voice communications.
Mission-critical data or intelligence information delivered to emergency responders on a reliable, secure IP-based emergency communication network with high speed performance. In particular, it provides emergency responders with information that assists them in doing their jobs. It allows mobile device users who are connected through the emergency communication network to wirelessly interrogate databases to gather useful information and to send or receive critical information to other mobile device users in the form of data. When a control room is connected to the emergency communication network, mission-critical broadband data may also be pro-actively sent or received by control room staff to emergency responders such as police officers, firefighters, and paramedics.
Wireless Internet access is commonly provided to mobile devices through cellular services and localized WiFi hotspots. However, access to WiFi and cellular networks is not available at all locations and expanded coverage to those locations may require the deployment of additional Cell Towers and raise environmental concerns. Likewise, access to a localized WiFi hotspot is not available at all locations and even when available at a current location of the mobile device, require continuous scanning for alternative WiFi hotspots and connections to another found WiFi hotspot to accommodate movement of the mobile device.
A wireless communication network which is to be deployed over a large geographical area generally requires a number of spatially distributed nodes for relaying communications between distant nodes in the network. Where the deployment of such a wireless communication network, however, spans an area such as an entire city, the component and installation costs of the network may be very large. Also, difficulties may arise in finding suitable locations for installing the nodes and procuring the necessary permissions to install the nodes at those locations. Also, there is often public objection to typical wireless network deployments which are bulky, unsightly, and/or have environmental concerns (e.g., EMI, noise emission).